The present invention generally relates to an open ended, woven fabric which is designed for use in a papermaking, cellulose or board manufacturing machine. The fabric has a plurality of loops at each end to form a seam for rendering the fabric endless.
As will be known to those skilled in the art, papermaking machines generally include three sections commonly referred to as the forming, press and dryer sections. The present invention finds particular application in the press section of a papermaking machine.
Typically, press felts include a supporting base, such as a woven fabric, and a paper carrying or supporting layer. Frequently, the paper support layer is a homogeneous, non-woven batt that has been affixed to the base. Base fabrics are typically woven fabrics which are used as an endless loop. Such an endless loop fabric may be woven endless with no seam or the fabric may be woven with two ends which are joined by a seam. Typical seams include pin type seams which utilize a pintle inserted through intermeshed seam loops to close the fabric.
Some prior art seams have employed threads in the seam area to increase batt adhesion in this area. However, these efforts have not always produced the desired sheet contact or loop length in the seam area. Additionally, some of the prior art seams do not provide the desired interconnection between paper and machine side machine direction threads. See U.S. Pat. Nos. 5,476,123 and 5,531,251. FIG. 1 shows a prior art seam area with a pair of additional threads A and B in complementary plain weave patterns interwoven in the fabric seam zone 40. Thread A weaves over and under paired MD threads and thread B weaves oppositely with the same pairs. In addition to not always providing the desired contact area, this seam has a loop length L which is larger than desired.
There exists a need to provide increased sheet contact in the seam zone through better batt anchorage, and a shortened loop length which is balanced between the paper and machine sides.